How does a diesel engine shut off

zaveriAs we all know, that in modern cars, and in self-starting motorcycles, starter motors are used to start the engine, using electric power.

Now the question is , how does the engine die down, when you turn off the ignition key ? In the case of a petrol engine, the power to the spark plug is cut off. Now what happens in the case of a diesel engine ?

Probably, the only way is that the power to fuel injector or fuel injection system is cut off. The engine won't run on air alone.

mechkyProbably, the only way is that the power to fuel injector or fuel injection system is cut off. The engine won't run on air alone.

I considered that possibility before, but then what is the mechanism ? is the power to the fuel feed pump cut off ?

zaveriI considered that possibility before, but then what is the mechanism ? is the power to the fuel feed pump cut off ?

These days both pump and injectors are electronically operated. All that is to be to done is to cut off power supply to the injection system. It is generally ECM controlled.

To stop a ordinary diesel engine ,the ones used in generators and small irrigation pump, diesel fuel supply to the engine is cut off.Usually a governor is provided to run the engine at the rated speed.It is this governor that we control, we pull the lever provided in this governor to cut off the fuel supply.In case of a single cylinder diesel engine , the mass of the flywheel will be high, so the engine continues to run for 10-15 secs, we have to cut off fuel supply till engine completely comes to a stop.
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Now consider the case of bus, the flywheel mass is less compared to that of a single cylinder engine, so as soon as fuel is cut off engine comes to a stop within 1-2 secs.